Transparent Endoscope Head Defining A Focal Length

ABSTRACT

A catheter configured for imaging objects substantially in focus is described herein. An imaging device is disposed on the distal end of the catheter. The imaging device has an effective focal plane that is located in front of the imaging device. The catheter also includes a transparent focal instrument that has an outer periphery that is positioned at the effective focal plane of the imaging device, to enable objects in contact with the outer periphery of the transparent focal instrument to be imaged substantially in focus.

PRIORITY

This application claims priority to U.S. Provisional Patent ApplicationNo. 61/132,566 filed on Jun. 18, 2008 and entitled, “TransparentEndoscope Head Defining a Focal Length” which is incorporated herein byreference in its entirety.

FIELD OF THE INVENTION

The present invention relates to medical devices, and more particularlyto miniaturized in-situ imaging devices and methods of operation of saiddevices.

BACKGROUND

The present invention relates generally to the field of endoscopy. Moreparticularly, the present invention relates to improved endoscopic andcatheter imaging.

Small imaging devices have become particularly useful in medicaldiagnostic and treatment applications. Portions of human anatomypreviously viewable only by a surgical procedure can be viewed now by aminimally invasive catheterization, provided an imaging device can bemade that is small enough to view the target anatomy.

Other uses for very small imaging devices are recognized. For example,such devices can be used and are desirable for surveillanceapplications, for monitoring of conditions and functions within devices,and for size- and weight-critical imaging needs as are present inaerospace applications, to name a few.

While the present invention has applications in these aforementionedfields and others, the medical imaging application can be used tofavorably illustrate unique advantages of the invention. Thedesirability of providing imaging at sites within the anatomy of livingcreatures, especially humans, distal of a small orifice or luminal spacehas long been recognized. A wide variety of types and sub-types ofendoscopes have been developed for this purpose.

One advance in imaging technology which has been significant is theincreased reduction of individual component sizes. Presently, chargedcoupled devices (CCD) such as miniature cameras can be manufactured soas to fit on the end of a catheter approximately the size of a couple ofstrands of wire. Lenses, optical fiber, and miniature surgical equipmentcan also be produces in miniature dimensions. However, these devicesalthough functional and increasingly effective, can be difficult toposition in order to appropriately image small areas of a target tissue.

For example, small cell carcinoma tends to start in the larger breathingtubes of the lungs. In its early stages it may only affect a smallnumber of cells, covering a distance of only 20-40 microns across.Because it could be advantageous to image and diagnose this problem inthis early stage before it rapidly grows and becomes quite large it isimportant to be able to access, locate and image these small areas. Highresolution imaging can effectively view these cells if such locationscan be found and if the imaging device can be appropriately positioned,focused, and imaged. This process is increasingly complicated in cases,such as small call carcinoma, wherein the cell clusters are located inlarge passageways. While a larger endoscope could be used for thisprocedure, a small catheter will substantially minimize patient traumaand duress. Presently, a user will be required to repeatedly move asmall catheter or endoscope forward-and-backward, side-to-side in atrial and error fashion in attempts to acquire the target area withinfocus of the miniature camera. Typically, this process results in imagesthat are not in complete focus and that can be difficult to diagnose.

SUMMARY

It has been recognized that it would be advantageous to develop acatheter that can be easily and effectively positioned so that a targetobject can be imaged substantially in focus.

Briefly, and in general terms, the invention is directed to a catheterconfigured for imaging objects substantially in focus. An imaging deviceis disposed on the distal end of the catheter. The imaging device has aneffective focal plane that is located in front of the imaging device.The catheter also includes a transparent focal instrument that has anouter periphery that is positioned at the effective focal plane of theimaging device, to enable objects in contact with the outer periphery ofthe transparent focal instrument to be imaged substantially in focus.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully apparent from the followingdescription and appended claims, taken in conjunction with theaccompanying drawings. Understanding that these drawings merely depictexemplary embodiments of the present invention they are, therefore, notto be considered limiting of its scope. It will be readily appreciatedthat the components of the present invention, as generally described andillustrated in the figures herein, could be arranged and designed in awide variety of different configurations. Nonetheless, the inventionwill be described and explained with additional specificity and detailthrough the use of the accompanying drawings in which:

FIG. 1 is a schematic illustration of an exemplary catheter inaccordance with principles of the invention;

FIG. 2 a is a side view of one embodiment of the catheter of FIG. 1;

FIGS. 2 b-2 d are side views of other embodiments of the catheter ofFIG. 1;

FIGS. 3 a-3 b is are side views of yet other embodiments of the catheterof FIG. 1;

FIG. 4 is a schematic illustration of a catheter having an inflatableballoon to position the imaging device in accordance with one embodimentof the invention;

FIG. 5 is a schematic illustration of an exemplary catheter having aninflatable balloon as a transparent focal instrument, in accordance withone embodiment of the invention;

FIGS. 6 a and 6 b are side views of one embodiment of the catheter ofFIG. 4;

FIGS. 6 c and 6 d are side views of an additional embodiment of thecatheter of FIG. 4;

FIGS. 7 a and 7 b are side views of one embodiment of the catheter ofFIG. 5;

FIG. 8 is a perspective view of one embodiment of the imaging device ofFIG. 2 a; and

FIG. 9 is a flowchart of a method for imaging with a catheter accordingto one embodiment of the present invention.

Reference will now be made to the exemplary embodiments illustrated, andspecific language will be used herein to describe the same. It willnevertheless be understood that no limitation of the scope of theinvention is thereby intended.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENT(S)

The following detailed description of exemplary embodiments of theinvention makes reference to the accompanying drawings, which form apart hereof and in which are shown, by way of illustration, exemplaryembodiments in which the invention may be practiced. While theseexemplary embodiments are described in sufficient detail to enable thoseskilled in the art to practice the invention, it should be understoodthat other embodiments may be realized and that various changes to theinvention may be made without departing from the spirit and scope of thepresent invention. Thus, the following more detailed description of theembodiments of the present invention, as represented in FIGS. 1 through9, is not intended to limit the scope of the invention, as claimed, butis presented for purposes of illustration only and to sufficientlyenable one skilled in the art to practice the invention. Accordingly,the scope of the present invention is to be defined solely by theappended claims.

The following detailed description and exemplary embodiments of theinvention will be best understood by reference to the accompanyingdrawings, wherein the elements and features of the invention aredesignated by numerals throughout. In describing and claiming thepresent invention, the following terminology will be used.

The singular forms “a,” “an,” and “the” include plural referents unlessthe context clearly dictates otherwise. Thus, for example, reference to“a camera device” includes reference to one or more of such cameradevices, and reference to “an inflatable balloon” includes reference toone or more of such an inflatable balloons.

As used herein, “catheter” refers to any one of a variety of catheter orendoscopic systems designed to imaging within the anatomy of livingcreatures or other appropriate system wherein imaging, surveillance, orother need is present. In one embodiment the catheter can comprises aminiature catheter having a SSID chip and a GRIN lens for imaging smalllocations with high resolution. Other imaging systems can beincorporated as will be apparent to one of ordinary skill in the art.

As used herein, “effective focal plane” or main focal plane refers toforward location in front of a camera/imaging device at which anobject(s) is/are substantially in sharp focus or “in focus”. It is notintended that this location be a single point in space, rather it isintended that this focal point refer to the two or three-dimensionalarea in which an imaging device can image an object substantially infocus. An object imaged at this distance from the camera, given theproper lighting conditions, can have higher resolution and increasedclarity than an object imaged at a closer or further distance. Thiseffective focal plane will vary with different camera and imagingdevices, as will be appreciated by one of skill in the art.

As used herein, “imaging device” refers to any one of the variety ofcatheter and endoscopic imaging devices, camera systems, fiber bundles,and other such devices known in the art. For example, the imaging devicecan include a SSID having an imaging array and a lens, as will bedescribed in greater detail below.

As used herein, “solid state imaging device” or SSID in the exemplaryembodiments generally comprises an imaging array or pixel array forgathering image data, and can further comprise conductive padselectrically coupled to the imaging array, which facilitates electricalcommunication therebetween. In one embodiment, the SSID can comprise asilicon or other semiconductor substrate or amorphous silicon thin filmtransistors (TFT) having features typically manufactured therein. Inanother embodiment, the SSID can comprise a non-semiconductor substratecoated with a semiconductor material, or other equivalent structure.Features can include the imaging array, the conductive pads, metaltraces, circuitry, etc. Other integrated circuit components can also bepresent for desired applications. However, it is not required that allof these components be present, as long as there is a means of gatheringvisual or photon data, and a means of sending that data to provide avisual image or image reconstruction.

“GRIN lens” or “graduated refractive index lens” refers to a specializedlens that has a refractive index that is varied radially from a centeroptical axis to the outer diameter of the lens. In one embodiment, sucha lens can be configured in a cylindrical shape, with the optical axisextending from a first flat end to a second flat. Thus, because of thediffering refractive index in a radial direction from the optical axis,a lens of this shape can simulate the affects of a more traditionallyshaped lens. In one embodiment, this is referred to as a GRIN rod lens.However, use of other suitable GRIN lens systems is contemplated for useherein.

As used herein, a plurality of items, structural elements, compositionalelements, and/or materials may be presented in a common list forconvenience. However, these lists should be construed as though eachmember of the list is individually identified as a separate and uniquemember. Thus, no individual member of such list should be construed as adefacto equivalent of any other member of the same list solely based ontheir presentation in a common group without indications to thecontrary.

With reference to FIG. 1, the invention is embodied in a catheter, showngenerally at 100, including an imaging device and a transparent focalinstrument 102 coupled to the catheter, at a distal tip of the catheter.The transparent focal instrument has an outer periphery that ispositioned at the effective focal plane of the imaging device. As shown,the outer periphery of the transparent focal instrument can be placed incontact with bodily tissue 104 so that the bodily tissue can be inposition to be “in focus” for imaging.

Because a target bodily tissue can be located in a relatively largebodily passage and because the catheter is relatively small, as shown inFIG. 1, it is often difficult to position the catheter 100 in properposition, such as in the free space of a large bodily passage, so thatit can position the target area “in focus” with respect to the camera.However, due to the nature of catheter systems the distal end of acatheter is frequently in contact with bodily tissue as it is directedalong curved bodily passages and cavities. When a semi-flexible catheteris directed along a bodily passage, for example, the lungs, veins, orgastrointestinal (GI) tract, the distal end of the catheter willtypically be in contact with the outer edge of these passages when beingdirected around a turn. At these points of contact, the catheter havingthe transparent focal instrument can effectively image the outer wallsof these passages in detailed and accurate focus.

The imaging device can include various camera and lens devices. In oneexemplary embodiment the imaging device can include a SSID chip 132 andGRIN rod lens 130, as shown in FIG. 8. The SSID can comprise a siliconor other semiconductor substrate or amorphous silicon thin filmtransistors (TFT) having features typically manufactured therein. Inanother embodiment, the SSID can comprise a non-semiconductor substratecoated with a semiconductor material, or other equivalent structure.Features including the imaging array 134, the conductive pads (notshown), metal traces (not shown), circuitry (not shown), etc., can befabricated therein. With respect to the conductive pads, the connectionbetween conductive pads and a conductive line of an umbilical orcatheter body can be through soldering, wire bonding, solder bumping,eutectic bonding, electroplating, and conductive epoxy. However, adirect solder joint having no wire bonding between the electricalumbilical and the conductive pads can be preferred as providing goodsteerability can be achieved with less risk of breaking electricalbonding. In one embodiment, the conductive line of the umbilical canprovide power, ground, clock signal, and output signal with respect tothe SSID. Other integrated circuit components can also be present fordesired applications, such as light emitting diodes (LEDs), forproviding light to areas around the GRIN rod lens.

It is not required that all of these components be present, as long asthere is a visual data gathering and sending image device present, andsome means provided to connect the data gathering and sending device toa visual data signal processor. Other components, such as the umbilical,housing, adaptors, utility guides, and the like, can also be present,though they are not shown in FIG. 8. The SSID 132 can be any solid stateimaging device, such as a CCD, a CID, or a CMOS imaging device. Also,the GRIN rod lens 130 can be coated with an opaque coating on the curvedsurface to prevent light from entering the lens at other than the flatsurface that is most distal with respect to the SSID. Additionalprinciples of operation and details of construction of similarmicro-camera assemblies can be found in U.S. patent application Ser.Nos. 10/391,489, 10/391,490, 11/292,902, and 10/391,513 each of whichare incorporated herein by reference in their entireties.

Reference will now be made to FIGS. 2 a-3 b, which depict variousembodiments of transparent focal instruments, in accordance with theprinciples of the invention. The catheter 100 includes an imaging device106. A transparent focal instrument 102 is coupled to the camera, forinstance, the transparent focal instrument can be coupled to the imagingdevice, as shown in FIGS. 2 a-2 b, or coupled to the catheter body asshown in FIGS. 2 c-3 b. The transparent focal instrument is configuredto have an outer periphery that is positioned at a distanceapproximately equal to the distance from the imaging device to theeffective focal plane of the imaging device. This distance isrepresented at 103.

As different camera systems can have varying angles of view, thetransparent focal instrument can have respectively varied shapes,contours, lengths, and other such properties. The exemplary embodimentsof FIGS. 2 a-3 b are intended to be presented herein as examples and arenot intended to be all inclusive regarding the type, shape, ordimensions of potential transparent focal instruments.

The transparent focus instrument 102 can be a hollow spacer, solidspacer, inflatable or inflated balloon, or other such device as will beapparent to one of ordinary skill in the art. The spacer can be composedof glass or a transparent polymer which includes common transparentplastics such as polystyrene, polycarbonate, or PET.

Multiple imaging devices 106 can be included on a single catheter, asshown in FIGS. 3 a-3 b. Accordingly, the transparent focus instrument102 can be configured to have an outer periphery at the effective focalplane of each imaging device. When conducting certain endoscopicprocedures it may be advantageous to include imaging devices that canimage in lateral directions. Typically, catheter devices have a limit tothe flexibility of the catheter body which limits the device's abilityto turn and face a lateral object when in small or narrow passageways.As such, by including an imaging device that faces in one or morelateral directions as well as one or more transparent focal instruments,respectively, the catheter can be directed down a narrow passage of thebody while imaging “in focus” the wall of the bodily passage.

In another embodiment the catheter 100 can include a turning device, asis known in the art. The turning device (not shown) can assist thecatheter to be directed to a target area of the body as well as turningthe distal end of the catheter, including the imaging device 106 andtransparent focal instrument 102 towards a target object or area. Thisturning device can assist as user to accurately position the peripheryof the transparent focal instrument in contact with a desired tissue.

FIG. 4 depicts the catheter 100 according to one embodiment of thepresent invention, being directed through a bodily passage 104. In thisexemplary situation, the bodily passage is substantially larger than thecatheter such that the transparent focal instrument is not naturally incontact with the passage wall. An inflatable balloon 110, coupled to thecatheter, which can be inflated to force the transparent focalinstrument in contact with the passage wall. Such a balloon can bedesigned and constructed by methods and materials currently known in theart.

FIGS. 6 a-6 b illustrate a function of the inflatable balloon 110represented in FIG. 4. As shown, the catheter can include alaterally-oriented imaging device 106 having a transparent focalinstrument 102 g. The inflatable balloon 116 is disposed on the sideopposite the imaging device and is attached to a fluid source 118configured to inflate and deflate the balloon 116 with a fluid. As shownin FIG. 6 a, the transparent focal instrument 102 g is not initially incontact with the bodily passage wall 104. FIG. 6 b shows a fluid 120being inserted into the balloon. The fluid can include air, oxygen,saline solution, or other fluid known in the art. As the balloon 116 isfilled with the fluid, the transparent focal instrument 102 g ispositioned in contact with the passage wall 104. As will be apparent,the balloon can include a variety of shapes and sizes according to theneeds of the user. In one embodiment, the balloon can be non-sphericallyshaped when inflated, to allow the passage of fluids within the bodilypassage, as shown in FIG. 4. In another embodiment, the catheter caninclude more than one inflatable balloon, which can each selectively beinflated to position the transparent focal instrument 102 g in contactwith a target object/location. In another embodiment, the ballooncomprises a toroidal or torus structure to allow the passage of fluidsthrough the otherwise occluded vessel.

Referring now to FIGS. 6 c through 6 d, a different method of laterallypositioning the transparent focal instrument is illustrated. In thisembodiment the balloon shown in FIGS. 6 a and 6 b is replaced with apiece of preformed wire 117, which when extended from the catheter 100forms a coil which moves the transparent focal instrument 102 g intocontact with a target object/location. In one embodiment, the preformedwire comprises a shape memory alloy such as Nitinol. In one aspect ofthe invention a plurality of imaging devices may be disposed lengthwisealong a side of the catheter body with corresponding focal instrumentsand positioning devices. In this manner, a practitioner may capturenumerous images of an interior of a patient as the catheter is advancedwithin the patient.

FIG. 5 depicts the catheter 100 according to one embodiment of thepresent invention, wherein the transparent focal instrument is in theform of a transparent inflatable balloon 112. When inflated thetransparent inflatable balloon has an outer periphery that is positionedat the effective focal plane of the imaging device, to enable objects incontact with the outer periphery of the transparent focal instrument tobe imaged substantially in focus. The use of a flexible, transparentballoon as a transparent focal instrument allows the catheter tomaintain miniature dimensions due to the relatively low volume andflexibility of the balloon. Additionally, the transparent balloon 112can act as an optical environment for the imaging device 106, displacingthe fluids and other material that can obstruct the imaging path of theimaging device.

FIGS. 7 a-7 b illustrate a function of the transparent balloon of FIG. 5according to one embodiment of the present invention. In one aspect ofthe invention, catheter 100 comprises a lumen 124 extending from adistal end of the catheter 100 to a side portion of the catheter. Whendeflated the transparent balloon 122 can be positioned along thecatheter body, as shown in FIG. 7 a effectively blocking the opening oflumen 124 on the lateral portion of the catheter body. As illustrated inFIG. 7 b, when inflated, the transparent balloon 122 can form atransparent focal instrument wherein the distance 103 from the imagingdevice 106 to the outer periphery of the inflatable balloon is equal tothe distance of the imaging device to its focal plane. When in itsinflated state, lumen 124 is open to the passage of fluids 126 throughthe vessel of the patient. Advantageously, while the distal end of thecatheter 100 effectively occludes passage of any fluids through thevessel of the patient, lumen 124 acts a temporary passageway for thefluids. While a single balloon-imaging device combination is shown, itwill be understood that a plurality of such combinations can be includedwith the present invention. In one exemplary embodiment of the inventionthe catheter can include four such combinations positioned around thecircumference of the catheter body. Each of these four transparentballoons can be selectively inflated, either synchronously or separatelyin order to image the walls of a bodily passage or bodily organ.Additionally, the transparent balloon-imaging device combination can bepositioned in a forward facing orientation, as shown in FIG. 5. Theballoon can be inflated with air, oxygen, saline solution, or otherfluid common to the art of balloon catheterization.

In another embodiment, the imaging device comprises a plurality ofmicro-cameras each having a different effective focal length andcorresponding transparent focal instrument attached thereto. In oneaspect, one of the plurality of imaging devices has a field of view thatis larger than the other imaging devices. In yet another aspect, one ofthe plurality of imaging devices has magnification capabilities. In yetanother aspect, the plurality of imaging devices may be orientedparallel to one another or may be configured in a non-parallelorientation as suits a particular application. Additional principles ofoperation and details of construction of GRIN lens microscope assembliescan be found in U.S. patent application Ser. No. 12/008,486 filed Jan.1, 2008 and entitled “Grin Lens Microscope System” which is incorporatedherein by reference in its entirety.

FIG. 9 is a flowchart of a method for imaging with a catheter. Themethod first includes providing a catheter with a transparent focalinstrument having an outer periphery that is positioned at the effectivefocal plane of an imaging device 210. The transparent focal instrumentcan be of a variety of configurations as described in detail above.Next, the method includes positioning the outer periphery of thetransparent focal instrument in contact with a target object, to enablea target object in contact with the outer periphery of the transparentfocal instrument to be imaged substantially in focus 220. Various methodand devices can be used to position the transparent focal instrument incontact with a target object. In addition to the methods and devicesdescribed above, the catheter body can be rotated around itslongitudinal axis and/or the imaging device can include turning devices,such as piezoelectric actuators, for tilting and/or moving the imagingdevice. Additionally, the focal length of the camera can be modified incertain cameras, while the distance between the imaging device and theouter periphery of the transparent focal instrument in respectivelymodified. Lastly, the target object is imaged by the imaging device 230.In one embodiment of the present invention, the imaging device can beconstantly imaging, so as to record and display live images to a user.Alternatively, the imaging device can include an additional feature,wherein enhanced images are selectively taken, that can be analyzed andviewed to assist in diagnosis and analysis.

Advantageously, embodiments of the present invention include atransparent focal instrument for a catheter to assist a medicalpractitioner to image objects that are in contact with the transparentfocal instrument substantially “in focus.” Thus, improved catheterimaging can be achieved by maneuvering the transparent focal instrumentin contact with a target tissue/object. Such a maneuver can reduce thetrial-and-error procedure of maneuvering the distal end of a catheterwithin a bodily passage/cavity. This can allow a user to image moretissue in less time and with higher resolution because the transparentfocal instrument can be passed over a potentially diseased area orquickly and repeatedly positioned against a passage wall as it isdirected down the passage. Additionally, this device can substantiallyenhance a catheter's ability to image critical tissue, such aspotentially cancerous cells/regions in higher definition and withincreased clarity, thus increasing a user's ability to diagnose andtreat problems. As such this device can dramatically improve a doctor'sability to detect various illnesses and diseases at their early stages.

While the forgoing examples are illustrative of the principles of thepresent invention in one or more particular applications, it will beapparent to those of ordinary skill in the art that numerousmodifications in form, usage and details of implementation can be madewithout the exercise of inventive faculty, and without departing fromthe principles and concepts of the invention. Accordingly, it is notintended that the invention be limited, except as by the claims setforth below.

1. A catheter configured for imaging objects substantially in focus,comprising: a) an imaging device disposed on a distal end of thecatheter, the imaging device having an effective focal plane located infront of the imaging device; and b) a transparent focal instrumentcoupled to the catheter, the transparent focal instrument having anouter periphery that is positioned at the effective focal plane of theimaging device to enable objects in contact with the outer periphery ofthe transparent focal instrument to be imaged substantially in focus. 2.The catheter of claim 1, wherein the transparent focal instrument is atransparent spacer.
 3. The catheter of claim 2, wherein the transparentspacer is composed of a material selected from a group consisting of apolystyrene, polycarbonate, or PET.
 4. The catheter of claim 1, whereinthe transparent focal instrument is a transparent inflatable balloon. 5.The catheter of claim 4, wherein the imaging device is disposed insideof the inflatable balloon and wherein the outer periphery of theinflatable balloon when inflated is configured to be positioned at theeffective focal plane of the imaging device.
 6. The catheter of claim 5,wherein the catheter further includes an open channel configured toallow fluid communication between a first orifice in the catheter and asecond orifice on the distal end of the catheter.
 7. The catheter ofclaim 6, wherein the inflatable balloon is configured to cover the firstorifice of the catheter when deflated for limiting fluid communicationin the open channel.
 8. The catheter of claim 1, wherein the imagingdevice comprises a SSID including an imaging array and a GRIN lensoptically coupled to the imaging array of the SSID.
 9. The catheter ofclaim 8, wherein the transparent focal instrument is coupled to the GRINlens.
 10. The catheter of claim 1, wherein the imaging device includesat least two imaging devices.
 11. The catheter of claim 1, wherein thecatheter includes a turning device configured to selectively turn thedistal end of the catheter in a plurality of directions.
 12. Thecatheter of claim 1, wherein the imaging device is configured to imagein a lateral direction.
 13. A catheter configured for imaging objectssubstantially in focus, comprising: a) an imaging device disposed on adistal end of the catheter, the imaging device having an effective focalplane located in front of the imaging device; b) a transparent focalinstrument, coupled to the catheter, having an outer periphery that ispositioned at the effective focal plane of the imaging device, to enablea target object in contact with the outer periphery of the transparentfocal instrument to be imaged substantially in focus; and c) apositioning device disposed near a distal end of the catheter andconfigured to selectively position the transparent focal instrument incontact with the target object.
 14. The catheter of claim 13, whereinthe positioning device comprises an inflatable balloon.
 15. The catheterof claim 13, wherein the positioning device comprises a preformed shapememory material disposed within a lumen of the catheter, wherein whenthe preformed shape memory material is extended outside the lumen of thecatheter it is biased in a coiled orientation and disposed to positionthe imaging device such that the transparent focal plane is in contactwith the target object.
 16. The catheter of claim 13, wherein theballoon is further disposed in a lateral facing direction opposite theimaging device and transparent focal instrument to selectively inflatein a lateral direction and position the transparent focal instrument incontact with the target object located aside the transparent focalinstrument.
 17. A method for imaging with a catheter, comprising: a)providing a catheter with a transparent focal instrument having an outerperiphery that is positioned at the effective focal plane of an imagingdevice; b) positioning the outer periphery of the transparent focalinstrument in contact with a target object to enable a target object incontact with the outer periphery of the transparent focal instrument tobe imaged substantially in focus; and c) imaging the target object. 18.The method of claim 17, wherein positioning includes inflating a balloondisposed on the catheter to move the transparent focal instrument incontact with the target object.
 19. The method of claim 17, furthercomprising: a) providing a balloon coupled to the distal end of thecatheter; and b) inflating the balloon to position the outer peripheryof the transparent focal instrument in contact with the target object.20. The method of claim 19, wherein the transparent focal comprises atransparent balloon having an inflated length substantially equivalentto the effective focal plane of the imaging device.